Posts Tagged ‘dtm’

[Editor’s note: Second of a pair of new satellites, now operational, will build higher resolution (with more vertical precision) view of Earth than prior SRTM efforts (90m free, 30m restricted). Graphic shows the same area in different DEM (DTM) resolutions. The 12 meter pixel size of the new commercial project is global, but inconsistent with the 10 meter DEMs available in the United States. Thanks Thierry_G!]

The TanDEM-X satellite has blasted into orbit on a mission to acquire the most precise 3D map of the Earth’s surface. The German radar spacecraft will fly in formation with an identical platform called TerraSAR-X launched in 2007. Together, the pair will measure the variation in height across the globe to an accuracy of better than two metres. Their digital elevation model will have myriad uses, from helping military jets fly ultra low to showing relief workers where an earthquake’s damage is worst.

“Our aim is to generate a model at a resolution and a quality that doesn’t exist today,” explained Dr Vark Helfritz, from satellite image-processing company Infoterra GmbH. “This will be a truly seamless global product – not a patchwork of datasets that have been fitted together,” he told BBC News. TanDEM-X was carried into space atop a converted intercontinental ballistic missile from the Baikonur Cosmodrome in Kazakhstan.

[Editor's note: Bart-Jan Dekker reminds me I've been negligent on mentioning Bernhard Jenny's latest project (and congrats to Bernie and Helen for their second child!). Bernie's previous work includes Flexprojector and Screepainter. The new update released 24 November fixes launching on some Windows OS machines that was semi-common.]

3D maps with progressive bending show the landscape using a varying viewing angle from steep in the foreground to flat in the background. The result is similar to the way in which passengers in a plane perceive the landscape, first looking straight downwards and then raising their gaze towards the horizon.

With progressive bending, 3D maps gain display depth, and landscape elements in the foreground are less obstructed from view than on 3D maps using a central perspective. More >>Terrain Bender Features

[Editor’s note: NASA and Japan’s Ministry of Economy, Trade and industry (METI) released new 30 meter resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) to the worldwide June 29, 2009. The new dataset covers the high latitudes with increased precision over SRTM, although the cloud cover problems that plauge ASTER can prove problematic. The servers were being hit heavy on Monday and data download is convoluted. The preview of the data uses a curious data exploration color ramp with inverted shading.Thanks Tom and Laris!]

PASADENA, Calif. – NASA and Japan released a new digital topographic map of Earth Monday that covers more of our planet than ever before. The map was produced with detailed measurements from NASA’s Terra spacecraft.

The new global digital elevation model of Earth was created from nearly 1.3 million individual stereo-pair images collected by the Japanese Advanced Spaceborne Thermal Emission and Reflection Radiometer, or Aster, instrument aboard Terra. NASA and Japan’s Ministry of Economy, Trade and Industry, known as METI, developed the data set. It is available online to users everywhere at no cost.

“This is the most complete, consistent global digital elevation data yet made available to the world,” said Woody Turner, Aster program scientist at NASA Headquarters in Washington. “This unique global set of data will serve users and researchers from a wide array of disciplines that need elevation and terrain information.”

According to Mike Abrams, Aster science team leader at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., the new topographic information will be of value throughout the Earth sciences and has many practical applications. “Aster’s accurate topographic data will be used for engineering, energy exploration, conserving natural resources, environmental management, public works design, firefighting, recreation, geology and city planning, to name just a few areas,” Abrams said.

Previously, the most complete topographic set of data publicly available was from NASA’s Shuttle Radar Topography Mission. That mission mapped 80 percent of Earth’s landmass, between 60 degrees north latitude and 57 degrees south. The new Aster data expand coverage to 99 percent, from 83 degrees north latitude and 83 degrees south. Each elevation measurement point in the new data is 30 meters (98 feet) apart.

“The Aster data fill in many of the voids in the shuttle mission’s data, such as in very steep terrains and in some deserts,” said Michael Kobrick, Shuttle Radar Topography Mission project scientist at JPL. “NASA is working to combine the Aster data with that of the Shuttle Radar Topography Mission and other sources to produce an even better global topographic map.”

NASA and METI are jointly contributing the Aster topographic data to the Group on Earth Observations, an international partnership headquartered at the World Meteorological Organization in Geneva, Switzerland, for use in its Global Earth Observation System of Systems. This “system of systems” is a collaborative, international effort to share and integrate Earth observation data from many different instruments and systems to help monitor and forecast global environmental changes.

NASA, METI and the U.S. Geological Survey validated the data, with support from the U.S. National Geospatial-Intelligence Agency and other collaborators. The data will be distributed by NASA’s Land Processes Distributed Active Archive Center at the U.S. Geological Survey’s Earth Resources Observation and Science Data Center in Sioux Falls, S.D., and by METI’s Earth Remote Sensing Data Analysis Center in Tokyo.

Aster is one of five Earth-observing instruments launched on Terra in December 1999. Aster acquires images from the visible to the thermal infrared wavelength region, with spatial resolutions ranging from about 15 to 90 meters (50 to 300 feet). A joint science team from the U.S. and Japan validates and calibrates the instrument and data products. The U.S. science team is located at JPL.

I went out to the Smithsonian’s Udvar-Hazy Air and Space museum annex at Dulles International Airport in Chantilly, Virginia last weekend and was pleasantly surprised to see one of the SRTM payloads hanging off the ceiling. The Shuttle Radar Telemetry Mapping program helped produce a significantly more accurate and detailed world-wide digital elevation model (DEM, DTM) in the early part of this decade and was a great leap forward for shaded relief generation. If you make the trip, you’ll find the SRTM between 22 and 23 on the map below in the “space shuttle” hanger. The map does a good job of indicating what altitude different aircraft can be found in the hanger.

In 2000, the Shuttle Endeavor carried the Shuttle Radar Topography Mission (SRTM) payload into orbit. Shuttle astronauts used the payload, manufactured by the AEC-Able Engineering Co., to map in high detail and three dimensions more than 70 percent of the Earth’s surface–the most complete and accurate rendering of the planet’s land masses ever attempted. The Museum possesses two components–the mast canister (this artifact) and the outboard support structure with its antennas–crucial to that mission.

To acquire this data, the SRTM used a novel hardware system that featured a main antenna located in the Shuttle payload bay, a folding mast (in the mast canister) that extended 60 meters from the Shuttle, and then another antenna system that was positioned at the end of the mast (the outboard structure). It was this dual antenna system–the largest rigid structure then flown in space–that produced, through interferometry (a technique for combining the information obtained from the two, separate antennas), a three-dimensional mapping of the Earth.

The mission was a joint undertaking of NASA’s Jet Propulsion Laboratory and the Department of Defense’s National Imagery and Mapping Agency. The military will use the highest resolution data from SRTM for terrain navigation for planes and cruise missiles. A lower resolution data set will be made available to civilian scientists and other users.